You will find North Biron Snowshelf Cave in the center of the three secret hot springs in the Hebra Mountains.
Cave Location
This cave is located at -3961, 3244, 0238 in the Hebra Mountains.
Explore the Cave
Go to the end of the cave and you find boulders in the floor. Break them and float down, and you will see some boulders in the south wall on your way down. Break those boulders to make hot spring water pour out.
Then break the boulders in the northeast wall, and the northwest wall, to reveal two more sources of hot spring water. This advances the quest Treasure of the Secret Springs.
Bubbulfrog Location
The Bubbulfrog is on the ceiling of the room with the wind gust in the middle.